Feuda Roberto, Marlétaz Ferdinand, Bentley Michael A, Holland Peter W H
Department of Zoology, University of Oxford, United Kingdom.
Department of Zoology, University of Oxford, United Kingdom
Genome Biol Evol. 2016 Feb 9;8(3):579-87. doi: 10.1093/gbe/evw015.
Opsin proteins covalently bind to small molecular chromophores and each protein-chromophore complex is sensitive to particular wavelengths of light. Multiple opsins with different wavelength absorbance peaks are required for color vision. Comparing opsin responses is challenging at low light levels, explaining why color vision is often lost in nocturnal species. Here, we investigated opsin evolution in 27 phylogenetically diverse insect species including several transitions between photic niches (nocturnal, diurnal, and crepuscular). We find widespread conservation of five distinct opsin genes, more than commonly considered. These comprise one c-opsin plus four r-opsins (long wavelength sensitive or LWS, blue sensitive, ultra violet [UV] sensitive and the often overlooked Rh7 gene). Several recent opsin gene duplications are also detected. The diversity of opsin genes is consistent with color vision in diurnal, crepuscular, and nocturnal insects. Tests for positive selection in relation to photic niche reveal evidence for adaptive evolution in UV-sensitive opsins in day-flying insects in general, and in LWS opsins of day-flying Lepidoptera specifically.
视蛋白与小分子发色团共价结合，每种蛋白质 - 发色团复合物对特定波长的光敏感。色觉需要多个具有不同波长吸收峰的视蛋白。在低光照水平下比较视蛋白反应具有挑战性，这解释了为什么夜行性物种常常丧失色觉。在这里，我们研究了27种系统发育不同的昆虫物种中的视蛋白进化，包括光生态位（夜行性、昼行性和晨昏性）之间的几次转变。我们发现五个不同视蛋白基因的广泛保守性，比通常认为的更多。这些包括一个c - 视蛋白加上四个r - 视蛋白（长波长敏感或LWS、蓝色敏感、紫外线[UV]敏感以及常被忽视的Rh7基因）。还检测到了一些近期的视蛋白基因重复。视蛋白基因的多样性与昼行性、晨昏性和夜行性昆虫的色觉一致。与光生态位相关的正选择测试揭示了一般日行性昆虫中紫外线敏感视蛋白以及特别是日行性鳞翅目昆虫的LWS视蛋白存在适应性进化的证据。
